Effects of extreme drought on community composition of arbuscular mycorrhizal fungi in the typical grasslands in Inner Mongolia during different growing seasons

Global climate warming and precipitation variability is expected to increase both the frequency and the intensity of climate extremes, such as severe drought. As a result, the composition of plant community changed and grassland gradually degenerated. Arbuscular mycorrhizal fungi (AMF) can from symbiotic association with the majority of terrestrial plants, which play an important role in plant resistance to environmental stresses. In order to explore the effects of extreme drought on AMF community structure, the experimental platform for simulating extreme drought, Maodeng pasture in Xilin city in Inner Mongolia, was selected as the research area in this study. Based on Illumina sequencing analysis, we measured the composition of AMF community and its relationship with environmental factors in soil ecosystem during different growing seasons under extreme drought. The results showed that: 1) 144 OTUs belonging to 8 genera and 5 families were identified in all samples, among which Glomus was the dominant genus in all treatments. 2) Compared with other extreme drought treatments, the extreme drought at the late growth season significantly reduced AMF colonization and extraradical hyphal length density (P < 0.05). 3) Extreme drought in different periods of the growing season did not significantly change the species richness of AMF, but Shannon-wiener index of AMF community was significantly increased under extreme drought in the late growing season (P = 0.01). Meanwhile, NMDS and PERMANOVA analysis showed that the community structure of AMF changed significantly (P = 0.022). 4) Soil organic carbon, C/N and pH were the main factors contributing to the difference ofchanged AMF community structure.